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LM66100: Oring config with one power source missing

Magnus Pihl
Prodigy 30 points
Part Number: LM66100


I read in the datasheet that the CE pin must not be left floating.

Now, please see datasheet "Figure 15. Dual Ideal Diode ORing"

Our application has one battery as power source and the other as a DC-plug for external power.

The external power source will not always be connected. The CE pin will then be more or less floating (only conencted to Vin of the other LM66100).

Is this OK? Or can I use 10-30Mohm resistor to a driving source?

Thanks in advance.

 .

  • 0
    TI__Guru 57737 points

    Hi Magnus,

    Our team is currently on Thanksgiving Holiday. Kindly expect a delay in response. 

  • 0 in reply to Praveen GD
    TI__Mastermind 32460 points

    Hi Magnus,

    Leaving CE floating won't guarantee a known on/off state when the external power source is disconnected, so best to pull it down with a resistor. The resistance you can use depends mainly on your application/EMI, so I would recommend prototyping and trying different values.

    Thanks,

    Patrick

  • 0
    Prodigy 30 points

    Hi.

    Thank you for your answer. Well, it is not really floating, as it is still connected to the other Vin. Is this still not recommended?

    Do you have any other IC that can act as a ORing configuration for two DC inputs where one sometimes will not be connected?

  • 0 in reply to Magnus Pihl
    TI__Mastermind 32460 points

    Hi Magnus,

    My intuition and experience says that there won't be an issue if you use two LM66100s - if by chance the "floating" input does go high enough to disable the device that should be active, the device that shouldn't be active will likely connect to VOUT and the floating input will discharge. However, it's still not recommended to leave the CE pin floating as it can be susceptible to fluctuating voltage in principle.

    As I said, I don't think it should be a problem, but the most reliable option would be to use LM66200, an integrated dual ideal diode/ORing device.

    Thanks,

    Patrick